             [cheshire.core :refer [generate-string]]
             [clojure.set :as set]))
 
+(def ^:private json-header
+  {"Content-Type" "application/json"})
+
 (defn sparql-query
   "Execute a SPARQL query in an HTTP GET request using `params` and HTTP `headers`."
   [{:keys [query]

                           (-> construct
                               (dissoc :lang)
                               (set/rename-keys {:construct :value})))]
    (generate-string (map format-construct sparql-constructs))))

(defroutes api-routes
  (context "/api" []

                                                 :query-params params
                                                 :throw-entire-message? true}))
      {:status 400
       :headers json-header
       :body (generate-string validation-results)})))

(defn get-exercise-solution
